1. Field of the Invention
This application relates to an injector for repairing vehicle windshields by means of application of vacuum for cleaning and de humidifying the damage area, and thereafter implanting a particular type of clear resin which has been developed for this purpose. The injector of the present invention is an essential part of a windshield repair system.
2. Description of Related Art
During the past thirty years, laminated glass has been used as safety glass in windows of automobiles and on all on-the -road vehicles. Laminated glass is commonly constructed of a front and a rear surface glass layer. These glass layers are bonded to an intermediate layer of a tough plastic material. This type of glass-plastic sandwich is designed to remain together during an accident, and is commonly called a safety glass windshield. When these windshields are cracked or damaged as the result of impact by stones or road debris, which may be thrown up from the road during travel, the outer layer of glass is usually damaged. Most often the intermediate plastic and the interior glass layers remain intact.
These damages take many forms, from simple crack lines to "stars", where additional cracks extend radially outward from the point of impact, and include "bulls eyes," where a stone has caused penetration of the outside layer of the windshield glass, without the radial cracks.
Long cracks require a different technique to repair because they cannot be subject to a vacuum therein, but these can be repaired using the present invention, as described in the referenced prior art.
Replacement of a windshields is very costly. The methods described herein were designed to create a permanent repair of the cracked or damaged region, negating the need to replace the entire windshield. Experience has shown that the greater preponderance of damages are on the outside pane of the glass sandwich. The instant invention can be used to repair the interior layer of glass as well as the outer glass layer, as may be required.
The development of clear and permanent flexible hard resins which are resistant to weathering has created an industry which is dedicated to field repair of cracked or damaged vehicle windshields. Dirt and water are removed from the damaged region by the application of a vacuum. A clear resin is then forced, under pressure, into the windshield damaged area. A second vacuum cycle may be required to remove air which has become entrapped in the resin during insertion. Afterwards, the resin is allowed to cure. Curing is accomplished by exposure to ultraviolet radiation. Ultraviolet radiation may be derived from sunlight or from a portable ultraviolet electric light. When the resin has the same refractive index and coefficient of expansion as glass, the repair is virtually invisible. These methods of repair are well known in the art, and are not repeated here. The major problems associated with the existing systems are the need for external hand or electric pumps to provide either pressure or vacuum, and the restricted degree of vacuum which can be obtained by a simple injector piston chamber. These problems are solved by the instant invention.
Many different injector designs have evolved during the past decade. Relevant prior art includes systems using electric or manual pumps to first generate the necessary vacuum for an injector followed by a resin fill of the injector, and the subsequent insertion of a resinous material into the damaged windshield area. In other cases, manually operated syringes are used for the same purpose, the syringe being attached to an injector device by means of a hose or tubing. The syringe provides both the vacuum and the pressure required for the repair.
Older designs have used special one or two part epoxies to repair the windshield. Modern systems embed a clear resin, having a coefficient of expansion and refractive index equal to that of window glass, inserted into the damaged area, resulting in a repair that is virtually invisible.
Prior art includes a WINDSHIELD REPAIR APPARATUS, U.S. Pat. No. 5,122,042 Issued to Einiger on Jun. 16, 1992. Other patents indicated therein are included by reference. Mr. Einiger's patent 5,122,042, describes a resin injector which is supported and held to the glass window by three conventional suction cups. These suction cups are equidistantly located in triangular shaped carrier. The injector mechanism is located at the geometrical center of the equilateral triangle which is formed by the three mounting suction cups. The injector is connected by a flexible tube to a manually operated syringe. In use, the repair apparatus is held to the surface of the window to be repaired by the three aforementioned suction cups. These suction cups are well known to those in the art. The details of operation are shown in the '042 patent A manually operated syringe is used to provide a partial vacuum to the damaged area on the outward stroke of the piston contained therein. Acetone solutions or other desiccating fluids may be used to clean the affected area. Several successive applications of cleaning fluid and vacuum stroke may be necessary to clean the cracked section if dirt has been allowed to accumulate therein. Afterwards, the same syringe is loaded with the resin which will be applied to the crack for repair. The syringe also provides the pressure required to insert the required resinous material into the damaged area, thus effecting the repair.
In the Einiger invention, U.S. Pat. No. 5,122,042, the manually operated pump is held between the palm and the fingers of the hand. The amount of vacuum or pressure is limited by the strength of the hand, and varies from user to user. Other variables which can affect the viscosity of the resin, such as age or temperature, can either contribute to or detract from the integrity of the repair.
U.S. Pat. No. 5,635,116 issued to Einiger on Jun. 3, 1997, describes a method for repairing damages in either the outside or inside glass using conventional crack expanders and resin injectors movably disposed on said cracks.
U.S. Pat. No. 5,670,180, issued to Randy L Mackey and Robert A, Beveridge, LAMINATED GLASS AND WINDSHIELD REPAIR DEVICE, issued Sep. 23, 1997. This patent addresses the variability and limitations of the manual syringe pump seen in the '042 patent. In the Mackey apparatus, U.S. Pat. No. 5,670,180, the syringe is replaced by a compound piston arrangement, driven by a manually rotated Acme thread and removable fixed pin. The Acme thread and the fixed pin cooperate to move the body of the Acme thread, which is integral to the injector piston, when the Acme thread is manually rotated. This kind of actuator provides constant pressure and is not dependent upon the variations in human strength. In this embodiment, a screw mechanism drives a dual piston arrangement. The upper piston having a large diameter, for efficient creation of the required vacuum. A lower section having a smaller diameter piston for pressurizing the resin to be applied to the windshield damaged area.
U.S. Pat. No. 4,954,300, GLASS REPAIR METHOD AND APPARATUS, issued on Sep. 4, 1990 to J. R. Dotson, describes an injector mechanism which must be heated to a temperature ranging between 75 degrees F. To 150 degrees F. in order to operate.
U.S. Pat. No. 3,993,520, WINDSHIELD REPAIR APPARATUS AND METHOD, issued on Nov. 23, 1976, to Werner et al, describes a method for inserting a clear liquid resin into a damaged windshield. Air bubbles are removed by using a vacuum. This 22 year old patent is now in the public domain, and describes the salient features of a windshield repair system.
U.S. Pat. No 5,589,018, GLASS REPAIR KIT AND METHOD OF USE, issued on Dec. 31, 1996 to Richard A. Campbell. This patent describes several different window repair devices, combinations of which may be used to implement a shatterproof window repair. These elements include devices similar to the previous art. These include resin and resin injectors, and support hardware.